Habitat Patchiness, Dispersal and Population Structure: Tests of Patch Dynamic and Demographic Models Using Small Mammals

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A recently developed class of models demonstrate that local population dynamics can be influenced by processes that operate between spatially separated sub-populations. In theory these models are directly applicable not only to understanding large- scale patterns of abundance but in evaluating the degree to which habitat fragmentation/patchiness affects species of concern. Critical factors in gauging species responses to habitat patchiness are: i) dispersal ability relative to patch isolation and dispersion; and ii) patch differences in social structure that determine whether individual patches are net producers or consumers of immigrants. Few studies, however, have examined the importance of these factors to field populations. Here we propose to study the responses of two small mammal species to an experimentally created landscape of habitat patches distributed over a 36 ha area. Sub-populations within the fragmented system would be compared to that in a continuous (unfragmented) habitat control. Objectives include examination of the interplay between patch size, animal dispersal ability, and how these affect--and are affected by--patch to patch variation in population structure. This system will serve as an empirical model for studying the importance of dispersal to populations inhabiting heterogeneous habitats, patches, and /or habitats that are threatened with fragmentation.